in music theory the circle of fifths or(circle of fourths)shows the relationship between the twelve tones of the chromatic scale,their corresponding key signatures,and the associated major and minor keys....

here is an idea. learn hey joe by jimi hendrix. every one of the chords is a 5th apart. C G D A E. the fifth's apart refer to the fact that they are 5 notes apart. C 2 3 4 G 2 3 4 D and so forth.

that's not exactly waht the circle of fifth's chart shows you but its a fun, easy song to play.

C G D A E E7
Hey Joe where ya' goin' with that gun in your hand?
C G D A E E7
I said hey Joe where ya goin' with that gun in your hand?
C G D A E E7
I'm goin' out to find my woman now she's been runnin' round with some other man
C G D A E E7
I said I'm goin' out to find my woman now she's been runnin' 'round with some other man

Learning theory should be taken on usually with some help from a teacher type role. It will vastly improve your understanding of music in general and will help you write music with slightly more ease later on(you will know the sounds you want and what to use to create it). I didn't start to learn theory until my Junior year of high school which was about 2 1/2 years ago... I have been playing for about 8 haha

Theory should be taken on when one is prepared to do it and when one wants to do it.

@null Its called a circle since it moves from one fifth to the next fifth to the next fifth to the next fifth.....it goes on until it eventually comes back to the original note. That's how we get our key signatures. C no sharps of flats, G the fifth has one sharp, D the fifth of G has two sharps,A the fifth of D has three sharps and so on and so on. Once you get to 6 sharps to keep the key signatures from duplicating you use flats. That is the main reason to learn the circle. I may be totally off but that's my best understanding.